Windows of various types are subject to air and water intrusion. In the case of water intrusion, window systems typically incorporate a drainage system, which includes one or more weep holes to allow the water to escape to prevent damage, such as corrosion, mold, deterioration of window seals, etc. While weep holes perform a beneficial drainage function, they can also allow air and energy infiltration and ex-filtration past the window system and consequent energy inefficiency, e.g., due to the gain or loss of heat into a building in which the window system is installed. Improvements in window systems remain desirable.